Conditioning of III-Nitride nanowire Light Emitting Diodes (LEDs)

Nanowire-based III-Nitride LEDs are attractive because they cover a wide range of band gap regions from deep UV to near IR, have a low defect density and can be grown on a variety of inexpensive substrates. However, the inhomogeneities of the nanowire ensemble result in a local variation of the current distribution and subsequently the LED efficiency. We used short-time overload (STO) voltages as a method to burn-out electrical shorts in order to homogenize the current flow. Using conductive atomic force microscopy (cAFM), by acquiring current maps at nanoscale, we show the existence and elimination of such nano-shorts due to STO. In macroscopic devices, these nano-shorts can be destroyed under a reverse bias. As a result, the threshold voltage and electroluminescence (EL) will increase. For UV nanowire LEDs, STO conditioning improved EL intensity by more than 200%.